This invention relates generally to high-frequency circuit devices, and more particularly to a high-frequency circuit device in which a plate-like member such as a printed circuit board, a shield plate structure and the like are accommodated within and fixed to a square-frame-formed casing. The plate-like member, making contact with an inwardly projecting part of the casing, is fixed to the casing through dip-soldering operation.
A typical example of a high-frequency circuit device is the electronic tuning type tuner unit for UHF which has a printed circuit board having shield plate segments projecting thereabove accommodated within a shield casing. Generally speaking, printed circuit boards of this type includes a number of circuits such as an antenna circuit, an RF circuit, a mixer circuit, an oscillator circuit, and an IF circuit, all of which are provided with their circuit elements. A plurality of shield plate segments are mounted on the printed circuit board or assembled along the boundaries of the individual circuits to shield the circuits from each other.
One example of a tuner unit known hitherto has adopted a mechanism for fixing a printed circuit board to a casing, in which mechanism the printed circuit board is fitted inside the casing together with a shield plate structure and is then fixed indirectly to the casing by soldering the shield plate structure to the inside surface of the casing. Accordingly, this fixing structure involves disadvantages in that, the setting or positioning of the printed circuit plate and the shield plate structure is apt to become unstable during the soldering work, thus degrading precision. Moreover, as the soldering work is carried out manually, the number of fabricating processes is large.
Furthermore, another example of a known tuner unit is of a construction in which a printed circuit board is accommodated within a casing in engagement with a slit-and-bent part inside the casing and is soldered and fixed thereto. This conventional construction has the same disadvantage as the construction just described, namely that the soldering work is performed manually thus causing instability in the positioning of the printed circuit board.